Rose Tyler, with all the fury of an eleven-year-old, slammed her maths homework on the kitchen table and sat glaring at it like it was some thoroughly annoying pest. Really, she just didn't understand it. How was she supposed to solve equations that had letters and all sorts of difficult rules? She hadn't gotten a single question right since they started the new module that week, and she was just about at the end of her rope.
Just then, before Rose had any time to invent insults to hurl at the book, there came a series of knocks and the chime of the doorbell. Rose hesitated by the table; the pattern was unfamiliar, and she wasn't supposed to answer the door for strangers. But Rose was in a rebellious sort of mood, so she went to greet whoever was knocking.
There was a tall man there, dressed in a brown suit and red bow-tie, and Rose could barely see matching suspenders. His hair was a bit long, flopping over his forehead, and perched on the top of his head was a fez. All in all, Rose thought him a very odd man.
"Can I help you?" Rose asked politely. She certainly didn't recognize him… perhaps he was friends with her mum.
"Hello, Rose Tyler," the man said with a grin. "I'm the Doctor."
"Doctor who?" Rose asked, a tad confused.
The man hesitated for a fraction of a second. "Doctor Smith. I've come to help you with your homework."
"Are you a maths professor?" He certainly didn't look like a normal professor.
"If you like," Doctor Smith said, still grinning. "I could be professor of whatever you need help with."
Rose considered him for a moment, then invited him in. "You can't stay long, Mum'll be home at five with supper."
"She won't even know I've been here," Doctor Smith promised, drawing a pair of x's on his chest.
Rose led him to the kitchen table, where he immediately picked up the maths book and began flipping through it.
"How d'you know my name?" Rose asked as she sank down opposite Doctor Smith.
"That's just how the world is, isn't it?" Doctor Smith said. "Grown-ups know your name and almost everything about you, and you don't have a clue who they are." He snapped the book shut and looked steadily at Rose. "I'm one of those grown-ups."
*Now, try to imagine how the Doctor is feeling at the moment. Not too long ago, he was having adventures with a Rose ten years older than the one in front of him. Rose would never see him like this again, and he would never see the Rose he knew again. She was the 'before' and he the 'after'. He would never again be able to visit the moments when they were truly together. That Rose was living happily with the duplicate of his previous regeneration, unaware of his aching hearts. But back to the story.*
Rose picked up her notebook and showed the assignment to Doctor Smith. "You can help me with this, can't you?"
Doctor Smith put on a hurt face that she didn't have complete faith in him. "Of course I can," he said, and he immediately went about explaining the mathematics in terms that somehow made perfect sense to Rose. Even though they had little more than two hours, they somehow managed to work through every question for the week, and by the time they were done Rose Tyler was ahead in her homework for the very first time.
"But you know," said Doctor Smith as they meandered to the door. "Things like that don't really matter. The stuff that will make you really happy…" he bent down so he was eye-level with Rose. "The thing that will make you the happiest girl in the universe… is companionship. To have someone to go on adventures with, someone who will always be there for you no matter what… find that, and you'll find true and complete happiness."
And the strange Doctor was gone.
As Rose grew up, she forgot the odd man in a fez and his advice. Until one day on a beach in Norway, as she walked hand-in-hand with the man she loved, the words echoed back through her mind. When she looked at her Doctor, she realized she'd found exactly what she had been unconsciously looking for for the past ten years. She smiled and knew that she would be blissfully happy for the rest of her life.